ARM: dts: at91: sam9x60-curiosity: Add raw NAND flash

ARM: dts: at91: sam9x60-curiosity: Add raw NAND flash

Basically the same as on sam9x60-ek.  Same as in Linux.  NAND flash is
correctly detected when booting into U-Boot:

    U-Boot 2023.07-rc6-00005-g12719f75dc-dirty (Jul 05 2023 - 13:06:35 +0000)

    CPU:   SAM9X60 128MiB DDR2 SiP
    Crystal frequency:       24 MHz
    CPU clock        :      600 MHz
    Master clock     :      200 MHz

    Model: Microchip SAM9X60 Curiosity
    DRAM:  128 MiB
    Core:  145 devices, 22 uclasses, devicetree: separate
    NAND:  512 MiB
    MMC:   sdhci-host@80000000: 0, sdhci-host@90000000: 1
    Loading Environment from FAT... Unable to read "uboot.env" from mmc0:1...
    In:    serial
    Out:   serial
    Err:   serial
    Net:   eth0: ethernet@f802c000
    Hit any key to stop autoboot:  0

Signed-off-by: Alexander Dahl <ada@thorsis.com>